For what it’s worth, Whitewings is completely unbonded. If I understand
galvanic corrosion correctly, you need a complete circuit for it to
occur. As all my seacocks are attached to rubber hoses, there doesn’t seem
to be a way, short of all hoses being full of water and interconnected, for
current to flow. Nigel Calder seems to support that approach and claims no
problems after years in the salt.
I do have a galvanic isolator in the shorepower system as that is an
obvious circuit through propshaft, engine, etc., if someone is dumping
stray current into the marina. A Nordic Tug across the dock from me was
doing exactly that two years ago and his underwater metals were basically
junk after one season. Aside from the usual Lake Michigan lime buildup, my
boat was fine and has stayed that way for three seasons.